Fuse indicator



p 6, 1932- F. c. LA MAR 1,876,426

FUSE INDICATOR Filed Nov. 22, 1929 ,3 Jig/Z INV NTOR M C. M

NEY

1 y ATTOR Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE FRANK C. LA MAR, OF NEW YORK, N. Y., ASSIGNOR TO GREAT WESTERN FUSE COM- PAINY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE FUSE INDICATOR Application filed November 22, 1929. Serial No. 408,985.

This invention relates to electrical fuses, especially to electrical fuses of the cartridge type, and more particularly to an indicator for such fuses which acts to give information as to the integrity of the fusible element.

It is well understood by those skilled in the electrical art that safety requires all circuits which carry or are capable of carrying 1 an appreciable amount of current have inserted safety devices in them to prevent an excessive flow of current under abnormal conditions.

A common safety device is the well known fuse made of a strip of metal which will melt upon the flow therethrough of an undesirably heavy current.

Fuses are made of many forms amongst which the cartridge fuse is a common type.

The cartridge fuse may be either of the ferrule type or the knife blade type. In either case, if it is of the renewable type, there is no convenient and desirable means of simple form by which the fact that the fusible metal has melted may be indicated except by removing the fuse from its position and disassemblin it.

A principal object of applicants invention is the provision of a means by which the integrity of the fusible elements of a fuse may be ascertained by a visual inspection without disassembling the fuse or disturbing the position thereof.

A further object of applicants invention is the provision of a means by which the integrity of the fusible element of a fuse may be ascertained by a visible inspection without disassembling the fuse or disturbing the position thereof, which may. be applied to the common forms of ferrule type fuses or knife blade types including a ferrule or cap, preferably by a simple manual operation, but at most not involving extensive permanent fastening means.

Other objects and advantages will appear as the description of the particular physical embodiment selected to illustrate the invention progresses and the novel features of the invention will be particularly pointed out in the appended claims.

In describing the invention in detail and the particular physical embodiments selected to illustrate the invention, reference will be had, to the accompanying drawing, and the several views thereof, wherein like characters of reference designate corresponding parts throughout the several views, and in which:

Figure 1 is a side elevational view of a common form of cartridge fuse with one form of my fuse indicator in place thereon; Fig. 2 is an end view of the fuse as shown by Fig. 1; Fig. 3 is a side elevational view of another form of fuse indicator of my invention applied to a well known form of cartridge fuse; Fig. 4 is atop plan view of the fuse as shown by Fig. 3; Fig. 5 is a side elevational view of another form of fuse indicator of my invention as applied to a well known form of cartridge fuse; Fig. 6 is an end elevational view of the device as shown by Fig. 5; Fig. 7 is a side elevational view of another form of fuse indicator of my invention as applied to a well known form of cartridge fuse; Fig. 8 is a perspective view of a clip usable with the device as shown in Fig. 7; Fig. 9 is a side elevational view of another form of fuse indicator of my invention as applied to a well known form of cartridge fuse; Fig. 10 is a top plan view of the device as shown by Fig. 9; Fig. 11 is a side elevational view of another form of fuse indicator of my invention as applied to a well known form of cartridge fuse; Fig. 12 is atop plan view of the device as shown by Fig. 11; Fig. 13 is a side elevational View of still another form of fuse indicator of my invention.

Numeral 1 throughout the figures designates the hollow tube made of insulating material and forming the body of the well known fuse either of the ferrule or knife blade type. 2 and 3 throughout the several views designate metallic ferrules one on each end of the body 1. 4 and 5 throughout the several views designate the Well known caps as used with the ferrule type fuse one being positioned on each end of the body 1 and engaging in any well known manner as by screw threading with the ferrules as 2 and 3.

Each of the hollow bodies 1 as shown in the mo drawing contains a. link 6 of easily fusible metal. This link is of comparatively large current carrying capacity as compared with the fusible wire 7. In all of the figures the fusible wire 7 is connected in shunt with the fusible link 6. I Vhen an abnormal flow of current occurs the fusible link 6 is disrupted and then the fuse wire 7 which is connected in shunt to the fusible link 6 is also disrupted. The fusible wire 7 is in full view, not enclosed in a case as is the fusible link 6 so that when the fusible wire 7 is disrupted it is visually apparent so that no necessity arises for taking the cartridge fuse out of position and disassembling it to ascertain whether or not the fusible link 6 has become disrupted.

In the form of fuse indicator as shown in Figs. 1 and 2 the fusible wire 7 is enclosed within a tube 8 of transparent material, preferably glass. The ends of the wire are suitably attached, one to the bracket 9 the other to the bracket 10. These brackets are metallic and are formed with a loop at the top, as shown in Fig. 2, which embraces the tube 8. In order to close the end of the tube applicant prefers to use a small mass of material such as sealing wax 11. The lower portion of the brackets as 9 are formed arcuate so as to have the same general curvature as the ferrules as 2. Each bracket is perforated with a large orifice as 12 and a smaller orifice as 13 so that the brackets may be positioned over two buttons as 14 and then by being given a motion about the longitudinal aXis of the cartridge as a center be moved so that the buttons lie over the smaller orifices as 13 with the heads of the buttons bearing upon the outside of the arcuate portion of the bracket and the underside 15 of the button. The underside 15 of the button is positioned such a distance from the surface of the ferrule 2 that a decided frictional engagement exists between the arcuate portion of the bracket, the button and the ferrule so that the bracket remains in the position in which it is placed.

If the indicator as shown in Figs. 1 and 2 becomes disrupted it merely requires a simple manual motion to remove the brackets from beneath the buttons and to put a new fuse wire as 7 in place supported by new brackets.

In Figs. 3 and 4 the form of indicator shown includes two glass tubes 8 each containing a fuse wire 7. Each of the glass tubes has, at each end, a metallic thimb-le as 16, to which the ends of the fuse wire 7 are electrically connected. The tube and thimbles are held between a metallic bracket 17 and a metallic bracket 18. The metallic brackets, as 17, are attached to the adjacent ferrules by any proper means as by soldering.

Over each of the brackets is positioned an insulating bar as 19, 20 and 21. Through each of these bars extend one or more fastening means which pass through the bar and through the brackets and into the body 1. In the drawing, screws are shown as at 20, 21, 22 and 23.

In the form of indicator shown by Figs. 5 and 6, a glass tube 8 is used enclosing a fuse wire 7. Upon the ends of the glass tube are metallic thimbles 24 and 25. The metallic thimbles rest in clips 26 and 27 which are attached to an insulating bar 28 by any approved means such as by the screw 29 and nut 30. The screw 29 and nut 30 not only fasten together the insulating bar 28 and a bracket but also attach metallic fingers as 33 and-34 one at each end of the insulating bar 28 to the bar. Each of the metallic fingers is also preferably held to the bar at another point, as by rivets 31 and 32, and have their ends bent at a right angle to the insulating bar 28 so as to make electrical contact with the caps as 4 and 5.

In Fig. 7 a glass tube 8 is used having a fusible wire 7 therein which has its ends electrically attached to the metallic thimbles 35 and 36. The thimbles are in electrical contact with the ferrules, as 2 and 3, and are maintained in position by a clip 37 shown in perspective in Fig. 8. This clip has a pair of larger fingers 38 and 39 made of spring material for embracing the body 1 of the fuse and a pair of smaller resilient fingers 40 and 41 for embracing the tube 8.

In Figures 9 and 10 the glass tube 8 is used with the wire 7 therein attached at each end to metallic thimbles as 35 and 36 which in turn are each attached as by soldering to a bracket as at 42 and 43. The brackets 42 and 43 are reversely positioned, that is, one has a base 44 directed to the right, as shown in Fig. 9, and the other has a base 45 directed to the left, as shown in Fig. 9. .Each of the bases has two perforations thereon one of large diameter as 46 and 47 and the other of small diameter as 48 and 49. The orifices as 46 and 48, and 47 and 49 in each base run one into the other so that the indicator may be positioned over two buttons as 50 and 51 with the large orifices as 46 and 47 aligning with the buttons and then the indicator may be pushed downwardly and moved endwise so that the base comes between the underside of the buttons and a ferrule. The distance between the underside of the button and a ferrule is made such that the fuse indicator is held frictionally in place.

In Figs. 11 and 12 the glass tubes 8 containing the fuse wire 7 is used together with the metallic thimbles as 35 and 36, but each thimble has a, small bracket, as 52 and 53, attached to it by any suitable means, as by soldering, which extends underneath the adjacent cap, as 54 and 55, making electrical connection therewith. v

In Fig. 13 the glass tube 8 with the fuse wire 7 therein and the metallic thimbles 35 and 36 are used but the brackets as 56 and 57 are attached to the body 1, as by screws 58 and 59, and electrical connection to each bracket is made by a small electrical conductor as 60 and 61 one end of which may be attached in any suitable manner as by solder to a bracket and the other end of which may extend under an adjacent cap as 54 and 55.

Although I have particularly described the principles underlying my invention and the construction of several forms thereof nevertheless, I desire to have it understood that the forms selected are merely illustrative and do not exhaust the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a cartridge fuse, in combination: a hollow elongated insulating body; metallic ferrules, one attached to each end of the body; a fusible link extending within the body between the ferrules and making electrical contact therewith a hollow transparent tube;

a fuse wire of relatively small current carrying capacity compared with the fusible link extending through the tube; metallic brackets, one surrounding each end of the tube and each connected with an end of the fusible wire, each bracket formed with a relatively large orifice and a connecting relatively small orifice; buttons, one on each ferrule, of a size to pass through the larger orifices in the brackets and be retained in the smaller orifices of the brackets whereby the fuse wire of relatively small current carrying capacity may be mounted with its ends in electrical contact with the ferrules.

2. In a cartridge fuse, incombination: a hollow elongated insulating body; metallic ferrules, one attached to each end of the body; a fusible link extending within the body between the ferrules and making electrical contact therewith; an indicator provided with two terminals; two metallic brackets, one connected to each of the terminals, each bracket formed with a relatively large orifice and a connecting relatively small orifice; buttons, one on each ferrule, of a size to pass through the larger orifice in the brackets and be retained in the smaller orifice of the brackets whereby the indicatorof relatively small current carrying capacity will have its terminals electrically connected with the ferrules. v FRANK, 0. LA MAR. 

